said by vexation:
that still doesnt answer my question
Stateful Packet Inspection, traditionally, is a form of routing that keeps track of connection states. For example, TCP has the "connected" state while UDP is connectionless so is virtually unaffected by SPI. Here's the way the internal workings *should* be:
With SPIOutgoing connection attempted from LAN-A to SITE-B.
SITE-B responds, parameters exchanged.
TCP state is "connected".
While state is "connected" forward all SITE-B to LAN-A.
TCP disconnects, kill connection immediately.
Without SPIOutgoing connection attempted from LAN-A to SITE-B.
For the next 4 minutes forward any SITE-B to LAN-A.
Any packets starts a new 4 minutes.
If no packets after 4 minutes, kill connection.
See the difference? SPI is one heck of a lot "smarter" and can do fancy things a LOT more efficiently and correctly.
Now... does LinkSys do this? Hmmmm... your guess is as good as mine. I still see no affect except it seems to be a global safety switch. Yes, enabling SPI turns off Port Forwarding, kills ping reply and the TCP "closed" reply. Someday I'll be playing with a packet generator and really see what it really does. Of course I'll post my results
.
How's that?